Before this commit, we had effective visibility as a part of FIR status,
so it was integrated into the full pipeline. In this commit,
we introduced "effective visibility as a service" which is now used
only by exposed visibility checker. This allows us to make the thing
universal for all FIR nodes, including nodes for Java / deserialized.
Synthetic property is var when it have setter. The latter is set up
in property when its parameter type is equal to getter return type. In
case of using @Nullable, parameter type of setter is not equal to
return type of getter, because the latter is flexible type. So to fix
this verification should occur using not null types
#KT-39076 Fixed
Before that commit we desugared `a ?: b` as
when (val elvis = a) {
null -> b
else -> elvis
}
It was incorrect, because `a` should be resolved in dependent mode,
but when it was `elvis` initializer it was resolved in independent
mode, so we can't infer type for `a` in some complex cases
Jinseong Jeon